Adds android.os.RecoverySystem (marked as pending) to replace the
(hidden) com.android.internal.os.RecoverySystem. RecoverySystem
contains methods for:
- verifying the signature of an update package
- rebooting to install a package
- rebooting to wipe user data
(The reboot functions require "android.permission.REBOOT" and
"android.permission.ACCESS_CACHE_FILESYSTEM".) Providing these
simplifies implementation of OTA update for device builders.
Change-Id: I63ce743b156e7a1a0327fd395b0e4a82c0eda79a